1. Field of the Invention
This invention relates to insulative cladding of walls of buildings, particularly to thermal and waterproof insulative cladding, and to insulation boards and battens of use in said cladding.
2. Description of the Related Art
Walls of buildings that are not formed of reinforced concrete typically comprise structural support members made of steel, concrete and like materials and having cladding disposed therebetween. The outer face of the cladding is generally provided with a decorative finish such as, for example, a polished granite slab, a brick wall or an exterior finish layer having an outer surface of a polymer/particulate decorative material. In the latter case, the exterior finish is also provided as a rain-fast surface.
Certain types of walls of buildings have an inner cavity between the outer cladding and an inner wall, typically consisting of a plasterboard material. The aforesaid cavity communicates with the outside atmosphere to provide an air pressure equalization chamber and water vent conduit for water ingressing through the outer cladding. Notwithstanding the high degree of care during construction to provide a water-impermeable i.e., rain-fast membrane to the outside cladding surface, over periods of time under the influence of wind and rain, temperature and frost and the like, hair-line cracks invariably are formed in the rain-fast layer to permit said ingress of moisture through the cladding to the cavity and into the interior of the building. Accordingly, the cavity must communicate with a weep or vent hole or channel to prevent build-up of water within the cavity.
One successful form of insulative cladding presently in use that does not require the presence of an inner cavity comprises a multi-layer insulation board having a typically 6-8 cm thick layer of insulating foam, such as, expanded polystyrene, polyurethane, urea-formaldehyde or mineral wool. Adhered to the inner surface of the foam layer is, typically, a gypsum plasterboard layer of approximately 2 cm thickness. On the outer surface of the foam layer is a reinforcing layer of two or more glass fibre meshes floated in a polymer-cement modified basecoat. This basecoat protects the foam insulation layer from both physical damage and moisture ingress. To the outer basecoat layer is provided an exterior decorative layer of a polymer-particulate material, typically, sand dispersed in an acrylic polymer.
Such multi-layer insulative cladding is formed, generally, as a handleable, rectangular batten or board of dimensions of 1.2 m.times.0.6 m.times.8 cm comprising 4.0 cm form insulative material.
Each of the composite layered battens or boards may be made in situ, i.e., the inner plasterboard and outer water-proofed layers may be adhered to the foam layer after the wall of insulative foam has been constructed, one batten upon another batten, during construction. Alternatively, the insulative battens and boards may be pre-fabricated and shipped to the construction site. The cladding comprising a plurality of the insulation boards or battens is formed by the plurality of insulation boards being cooperatively bonded in adjacent relationship as to provide insulation to the wall. Such construction lies well within the skill of plasterboard tradesmen. Battens are abutted one on top of and next to other similar battens and caulked or the like to fill in any gaps or voids between battens. Suitable connections to the structural supports of the walls of the building are made.
In considering the desirability of a particular type of insulative cladding for use in a wall, regard must be had to the effect of wind pressure and rain on the outer wall. In the absence of direct communication between the outside atmosphere and the atmosphere inside the building and/or any-cavity, significant air pressure differentials may exist dependent on the wind speed and the like. In consequence of this relatively large pressure differential between the outside and inside of the building created by strong winds acting on the wall, significant water ingress through hair-line cracks and other unintentional openings and the like readily occurs. In the absence of a cavity in the wall, such moisture will reach and damage the inside surface of the wall of the building. Accordingly, cavities are most preferred in walls, to prevent water ingress, provided the cavity is vented to atmosphere to allow for pressure equalization and accumulative water run-off out of the cavity. Thus, cladding systems relying solely-on outer face sealing materials suffer the risk of water ingress over time, enhanced by air pressure differentials, rain, and successive freezing and thawing of water contained within the cladding.
Thus, while the composite layered cladding of the prior art provides a generally satisfactorily cladding which readily enables a decorative cladding system of a wall to be satisfactorily and quickly constructed, such a resultant wall often suffers from the effects of water damage under the air pressure differentials as aforesaid described, in the absence of an outside air-vented cavity.